Patent Reference 1 mentioned below discloses a technology relating to a vehicle seat that incorporates a side airbag apparatus. Specifically, an airbag module of the side airbag apparatus is attached, via a bracket, to a side frame that is at a side of a seatback frame that opposes a vehicle body side portion. A webbing (a sheet-shaped member) is provided so as to enclose the airbag module and the side frame. The webbing is divided in two, between an inner side and an outer side. Front end portions of these left and right webbings are respectively sewn to two ends of a cleaving portion (an opening portion) of a cover of the vehicle seat. Rear end portions of the left and right webbings are sewn to one another.
In a case according to the vehicle seat described above, an assembly procedure of the vehicle seat equipped with a side airbag apparatus is as follows. First, the front end portions of the two divided webbings are preparatorily sewn to the two end portions of the cleaving portion of the cover of the vehicle seat. Thereafter, a seatback pad of the vehicle seat is covered with the cover in this state. Then, the airbag module having being preparatorily attached to the side frame at the vehicle width direction outer side of the seatback frame, the seatback pad is assembled to the seatback frame. Finally, the rear end portions of the left and right webbings are joined by sewing at the rear side of the airbag module.